Metabolomic analysis and bioactivities of Arbutus unedo leaves harvested across the seasons in different natural habitats of Sardinia (Italy)

Background: Arbutus unedo L. is a wild tree of Mediterranean regions used as food and in traditional medicine and important for afforestation programs. There is no detailed information available on the variation of A. unedo leaves metabolome across the seasons. The leaves were analyzed by Proton nuclear magnetic resonance (1 H NMR)-based metabolomics, comparing samples harvested across the seasons and in ten different natural habitats of Sardinia (Italy). Results: Multivariate analysis showed the impact of seasonal variation on the metabolome: glucose and quinic acid increased in summer, while in spring sucrose was accumulated. β-Arbutin, the main known active principle of A. unedo, generally reached the highest concentration in autumn. In winter, O-β-methylglucose, γ-aminobutyric acid (GABA), flavonols (quercetin-3-O-α-rhamnoside, myricetin-3-O-α-rhamnoside, kaempferol-3-O-α-rhamnoside), catechin, and gallocatechin increased. Characteristic metabolomic features were found also for samples collected in different locations. For instance, trees growing at the highest altitude and exposed to lower temperatures produced less flavonols and catechins. The only sample collected on trees growing on limestones, dolomites, and dolomitic limestones type of soil showed generally the highest content of arbutin. The highest phenolics content was found during spring, while samples collected on flowering branches in winter were the ones with the highest flavonoid content. The antioxidant activity was also variated, ranging from 1.3 to 10.1 mg of Trolox equivalents (TE)/mL of extract, and it was positively correlated to both total phenolics and flavonoid content. Winter samples showed the lowest antibacterial activity, while summer and autumn ones exhibited the highest activity (IC50 values ranging from 17.3 to 42.3 µg/mL against Staphylococcal species). Conclusion: This work provides 1 H-NMR fingerprinting of A. unedo leaves, elucidating the main metabolites and their variations during seasons. On the basis of arbutin content, autumn could be considered the balsamic period of this taxon. Samples collected in this season were also the most active ones as antibacterial. Moreover, an interesting metabolomic profile enriched in catechins and flavonols was observed in leaves collected in winter on flowering branches which were endowed with high antioxidant potential

Identification of chalcone-based antileishmanial agents targeting trypanothione reductase

All currently used first-line and second-line drugs for the treatment of leishmaniasis exhibit several drawbacks including toxicity, high costs and route of administration. Furthermore, some drugs are associated with the emergence of drug resistance. Thus, the development of new treatments for leishmaniasis is a priority in the field of neglected tropical diseases. The present work highlights the use of natural derived products, i.e. chalcones, as potential source of antileishmanial agents. Thirty-one novel chalcone compounds have been synthesized and their activity has been evaluated against promastigotes of Leishmania donovani; 16 compounds resulted active against L. donovani in a range from 3.0 to 21.5 μM, showing low toxicity against mammalian cells. Among these molecules, 6 and 16 showed good inhibitory activity on both promastigotes and intracellular amastigotes, coupled with an high selectivity index. Furthermore, compounds 6 and 16 inhibited the promastigote growth of other leishmanial species, including L. tropica, L. major and L. infantum. Finally, 6 and 16 interacted with high affinity with trypanothione reductase (TR), an essential enzyme for the leishmanial parasite and compound 6 inhibited TR with sub-micromolar potency. Thus, the effective inhibitory activity against Leishmania, the lack of toxicity on mammalian cells and the ability to block a crucial parasite's enzyme, highlight the potential for compound 6 to be optimized as novel drug candidate against leishmaniasis

Serological and molecular tools to diagnose visceral leishmaniasis: 2-years' experience of a single center in Northern Italy

The diagnosis of visceral leishmaniasis (VL) remains challenging, due to the limited sensitivity of microscopy, the poor performance of serological methods in immunocompromised patients and the lack of standardization of molecular tests. The aim of this study was to implement a combined diagnostic workflow by integrating serological and molecular tests with standardized clinical criteria. Between July 2013 and June 2015, the proposed workflow was applied to specimens obtained from 94 in-patients with clinical suspicion of VL in the Emilia-Romagna region, Northern Italy. Serological tests and molecular techniques were employed. Twenty-one adult patients (22%) had a confirmed diagnosis of VL by clinical criteria, serology and/or real-time polymerase chain reaction; 4 of these patients were HIV-positive. Molecular tests exhibited higher sensitivity than serological tests for the diagnosis of VL. In our experience, the rK39 immunochromatographic test was insufficiently sensitive for use as a screening test for the diagnosis of VL caused by L. infantum in Italy. However, as molecular tests are yet not standardized, further studies are required to identify an optimal screening test for Mediterranean VL

Diagnostic workflow for visceral leishmaniasis (VL).

<p>*As serological tests, the rapid rK39-based immunochromatographic test (ICT) was performed. Subsequently, the indirect immunofluorescence test (IFAT) was carried out for antibody titration in all ICT-positive cases. IFAT was also performed in PCR-positive/ ICT-negative cases and when test result for ICT was uncertain. BM, bone marrow.</p

Clinical data, laboratory tests and outcome of patients with visceral leishmaniasis, July 2013 –June 2015.

<p>Clinical data, laboratory tests and outcome of patients with visceral leishmaniasis, July 2013 –June 2015.</p

Performance of serological and molecular tests for diagnosis of visceral leishmaniasis, VL (n = 94).

<p>VL cases were identified by comprehensive diagnostic criteria, ie clinical and parasitological criteria.</p